Momentum relaxation of a charged particle by small-angle Coulomb collisions

Chaotic electromagnetic fields are common in many relativistic plasma environments, where they can be excited by instabilities on kinetic spatial scales. When strong electric fluctuations exist on sub-electron scales, they may lead to small angle, stochastic deflections of the electrons’ pitch angles. Under certain conditions, this closely resembles the effect of Coulomb collisions in collisional plasmas. The electric pitch-angle diffusion coefficient acts as an effective collision – or ‘quasi-collision’ – frequency. We show that quasi-collisions may radically alter the expected radiative transport properties of candidate plasmas. In particular, we consider the quasi-collisional generalization of the classical Faraday effect.

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Description of a charged-particle curvilinear beam in the small-angle approximation

Doklady Physics ◽

10.1134/1.1355376 ◽

2001 ◽

Vol 46 (2) ◽

pp. 69-71

Author(s):

N. D. Naumov

Keyword(s):

Charged Particle ◽

Small Angle ◽

Small Angle Approximation ◽

Curvilinear Beam

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Investigation of Detection Threshold Variation and Microcrystallite Nucleation in Nuclear Track Detectors Using Small Angle X-Ray Analysis

Advances in X-ray Analysis ◽

10.1154/s0376030800016566 ◽

1978 ◽

Vol 22 ◽

pp. 213-220

Author(s):

A. Aframian

Keyword(s):

Charged Particle ◽

Small Angle ◽

Detection Threshold ◽

X Ray Diffraction ◽

X Ray ◽

Density Distributions ◽

Nuclear Track Detectors ◽

Nucleation Sites ◽

Energy Relationships ◽

Threshold Variation

The variations in the threshold registration of a number of plastic dielectric nuclear track detectors, DNTD's, have been investigated in terms of range energy relationships and the changes in structure affecting electron density distributions studied, using small angle X-ray diffraction. A similar mechanism has been employed to investigate the presence and formation of microcrystallite nucleation sites in lunar and terrestrial minerals, following proton and charged particle bombardments of 10-18 particles/cm2.

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Small Angle Electron Scattering From Vacuum Condensed Metallic Films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101657 ◽

1968 ◽

Vol 26 ◽

pp. 380-381

Author(s):

J. Silcox ◽

R. H. Wade

Keyword(s):

Electron Scattering ◽

Small Angle ◽

Ring Structure ◽

Two Dimensional ◽

Metallic Films ◽

Micro Structure ◽

Angle Scattering ◽

The Fourier Transform ◽

Source Of Information ◽

Kinematical Theory

Recent work has drawn attention to the possibilities that small angle electron scattering offers as a source of information about the micro-structure of vacuum condensed films. In particular, this serves as a good detector of discontinuities within the films. A review of a kinematical theory describing the small angle scattering from a thin film composed of discrete particles packed close together will be presented. Such a model could be represented by a set of cylinders packed side by side in a two dimensional fluid-like array, the axis of the cylinders being normal to the film and the length of the cylinders becoming the thickness of the film. The Fourier transform of such an array can be regarded as a ring structure around the central beam in the plane of the film with the usual thickness transform in a direction normal to the film. The intensity profile across the ring structure is related to the radial distribution function of the spacing between cylinders.

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Small-Angle Electron Scattering (SAES) of Polymers

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100117467 ◽

1985 ◽

Vol 43 ◽

pp. 78-79

Author(s):

Ralph Oralor ◽

Pamela Lloyd ◽

Satish Kumar ◽

W. W. Adams

Keyword(s):

Electron Scattering ◽

Small Angle ◽

Angular Resolution ◽

Structural Features ◽

Objective Lens ◽

High Angular Resolution ◽

Push Button ◽

First Case ◽

Diffraction Mode ◽

Very High

Small angle electron scattering (SAES) has been used to study structural features of up to several thousand angstroms in polymers, as well as in metals. SAES may be done either in (a) long camera mode by switching off the objective lens current or in (b) selected area diffraction mode. In the first case very high camera lengths (up to 7Ø meters on JEOL 1Ø ØCX) and high angular resolution can be obtained, while in the second case smaller camera lengths (approximately up to 3.6 meters on JEOL 1Ø ØCX) and lower angular resolution is obtainable. We conducted our SAES studies on JEOL 1ØØCX which can be switched to either mode with a push button as a standard feature.

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